title: Oxygen supplementation in noninvasive home mechanical ventilation: the crucial roles of CO2 exhalation systems and leakages.
abstract: BACKGROUND
  When supplemental oxygen is added to noninvasive ventilation using a non-ICU ventilator, it is usually introduced with a preset flow into the circuit near the ventilator; however, the impact of different CO2 exhalation systems and leaks on the actual FIO2 and gas exchange has not been elucidated.
  
  
  METHODS
  In a randomized, open-label, 4-treatment (2-by-2), 4-period crossover design, 4 daytime measurements (60 min each) were performed in 20 subjects receiving home mechanical noninvasive ventilation plus supplemental oxygen (≥ 2 L/min) inserted near the ventilator: active valve circuit or leak port circuit with or without artificial leakage (4 mm inner diameter). Oxygen concentration near the ventilator, oxygen concentration at the mask, and blood gases were measured.
  
  
  RESULTS
  Overall, oxygen concentration at the mask (29 ± 5%) was lower than oxygen concentration at the ventilator (34 ± 4%), with a mean difference of 5.1% (95% CI 4.2-5.9%, P < .001)%. With the leak port circuit, oxygen concentration at the mask decreased by 3.2% (95% CI 2.6 to 3.9%, P < .001), compared to the active valve circuit. When artificial leakage was introduced into the circuit, oxygen concentration at the mask decreased by 5.7% (95% CI 5.1 to 6.4%, P < .001)%, PaO2 by 10.4 mm Hg (95% CI 3.1 to 17.7 mm Hg, P = .006), and PaCO2 increased by 1.8 mm Hg (95% CI 0.5 to 3.1 mm Hg, P = .008).
  
  
  CONCLUSIONS
  The use of a leak port circuit and the occurrence of leak around the interface significantly reduced oxygen concentration at the mask and negatively impacted gas exchange in subjects receiving home noninvasive ventilation and supplemental oxygen. (German Clinical Trials Registry, www.drks.de, DRKS00000449).
authors.affiliation: Department of Pneumology, University Hospital, Freiburg, Germany.
authors.forename: Jan H
authors.initials: JH
authors.lastname: Storre
authors.forename: Sophie E
authors.initials: SE
authors.lastname: Huttmann
authors.forename: Emelie
authors.initials: E
authors.lastname: Ekkernkamp
authors.forename: Stephan
authors.initials: S
authors.lastname: Walterspacher
authors.forename: Claudia
authors.initials: C
authors.lastname: Schmoor
authors.forename: Michael
authors.initials: M
authors.lastname: Dreher
authors.forename: Wolfram
authors.initials: W
authors.lastname: Windisch
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002245:Carbon Dioxide; D018592:Cross-Over Studies; D004417:Dyspnea / Q000628:therapy; D004868:Equipment Failure; D045853:Exhalation; D005260:Female; D006801:Humans; D008297:Male; D008397:Masks; D008875:Middle Aged; D063087:Noninvasive Ventilation / Q000295:instrumentation*; D010100:Oxygen / Q000008:administration & dosage* / Q000032:analysis; D010102:Oxygen Inhalation Therapy / Q000295:instrumentation*; D010313:Partial Pressure; D011659:Pulmonary Gas Exchange
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen
keywords: COPD; chronic respiratory failure; long-term oxygen therapy; mechanical ventilation